The Reagan administration exaggerates the extent of Soviet cheating on arms control agreements, according to an extensive study by Stanford University researchers. In turn, the Soviet Union has exploited ambiguous arms-treaty provisions and responded to United States charges with a nonconstructive ``so's your old man'' attitude. The result, the study says, is a crisis in relations that is very real, even though it is based on false perceptions.

``The patterns of behavior exhibited by the US and Soviet Union today lead down the road toward dismantling arms control,'' concludes the report, produced by Stanford's Center for International Security and Arms Control.

Today there are 20 agreements between the superpowers that deal in some way with the control of nuclear arms. Of these, 11 have quietly remained in force with neither side complaining about the other's relevant behavior. Such uncontroversial pacts range from the 1971 Seabed Arms Control Treaty, which prohibits nuclear arms on the sea floor, to the several hotline agreements, which have established a permanent open line of US-Soviet communications.

Since 1983, eight agreements have been the target of complaints about cheating by both the US and the Soviet Union. The most publicized charges deal with two pacts: the 1972 Anti-Ballistic Missile Treaty (ABM), which limits development and deployment of antimissile forces, and the 1979 SALT II limits on numbers and types of nuclear arms. SALT II was signed by both nations, but never ratified by the US Senate. Last fall, the US surpassed SALT II limits by deploying B-52 bombers with cruise missiles.

Of the many accusations flung about, Stanford researchers judged only one to be a clear-cut violation of a treaty in force: the Soviet Union's Krasnoyarsk radar. Under the ABM Treaty, such powerful phased-array radars as Krasnoyarsk are to be located on the edge of a nation's territory, looking outward. Such siting means they could be used for early warning of a missile attack but not as control centers for antimissile forces.

As the Stanford study points out, Krasnoyarsk is located 400 miles from the nearest border, and its beam points northeast across 3,000 miles of Soviet territory.

Also, the study cited three examples of questionable treaty compliance. One involves upgrades of US early-warning radars at Thule, Greenland, and Fylingdales Moor, England, both of which could be interpreted as ABM Treaty violations.

A second is apparent Soviet encryption of telemetry, electronic signals emitted by missiles in flight. The superpowers eavesdrop on telemetry to learn about each other's nuclear arsenal, and encryption that prevents this sizing-up is prohibited by SALT II.

The third questionable activity is Soviet deployment of the SS-25 mobile missile. The US claims the SS-25 is an all-new weapon that violates SALT restrictions on allowable numbers of missile types. The Soviet Union claims it's just an upgraded SS-13, and thus permissible.

But the Stanford study says that the military importance of the one clear violation and the three possible ones is limited. Far more important, it says, is the fact that both nations have adhered to the central provisions of arms agreements. Until the US unilaterally withdrew from SALT II last November, neither side broke the treaty's ceilings on numbers of allowable weapons. According to the study, this preserved ``the essential stability of the nuclear balance.''

The report judges that all other charges of treaty cheating do not hold up. They involve issues that have already been resolved, are based on questionable evidence, or involve treaty language that the two sides interpret differently.

US charges that the Soviet Union has violated the 150-kiloton yield limit for underground nuclear tests set by the Threshold Test Ban Treaty are unsupportable, say the Stanford researchers, considering how little is known about measuring such tests. The US says Soviet Flat Twin radars are mobile, and thus banned by the ABM Treaty. The radars, however, do not have wheels and take several days to erect.

Yet perceptions of treaty cheating have had a real political effect. Reagan officials cited cheating as a major reason for US withdrawal from SALT II. US and Soviet countercharges that the other one is racing to break out of the ABM pact may have created a tense situation in which these allegations become self-fullfilling prophecies, the Stanford study says.

Among other things, the study recommends that:

In the future, the administration's annual report to Congress on Soviet treaty violations should also contain assessments of Soviet treaty compliance, and of possible US pact violations.

The US should try to refurbish the dispute-resolution mechanism of the Standing Consultative Commission. The SCC, a forum established for both sides to air complaints about arms treaty compliance, recently has been more of a forum for bickering.